Lip type seal

Details Lip type seal Lip type seal

2001-03-16

2002-07-23

Knight, Anthony (Department: 3626)

Seal for a joint or juncture

Seal between relatively movable parts

Circumferential contact seal for other than piston

C277S549000, C277S572000, C277S579000, C277S580000

Reexamination Certificate

active

06422570

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a lip type seal which seals the circumference of a rotary shaft of various sorts of equipments.
PRIOR ART
As shaft seal technology using a lip type seal, have a structure as shown in
FIG. 4
is conventionally known.
In
FIG. 4
, reference numeral
100
designates a housing of a shaft hole part of an equipment. Numeral
200
designates a lip type seal which is installed to a seal installation part
101
formed on an inner circumferential surface of the housing
100
, and seals the circumference of a rotary shaft
102
.
In the lip type seal
200
, on an inner circumference of an outer ring part
201
with a packing
201
a
and a metal ring
201
b
fixed integrally, a seal main body
202
constituted by an annular sheet made of a synthetic resin such as a fluorine resin and a rear surface support plate
203
constituted by an annular metal plate disposed on the rear side of the seal main body
202
are fixed by caulking of the metal ring
201
b
. The outer ring part
201
is tightly fitted to the inner circumferential surface
101
a
of the seal installation part
101
in the housing
100
by the packing
201
a
. An inner circumferential surface of a seal lip
202
a
formed on the inner circumferential surface of the seal main body
202
and extending to the side of the sealed space A is sealably brought into slidable contact with the outer circumferential surface of the rotary shaft
102
. Therefore, a fluid as a seal object within a sealed space A is prevented from leaking to the side of an atmosphere B outside the equipment.
In the above-mentioned conventional lip type seal, the rear surface support plate
203
restricts deformation of the seal main body
202
to the side of the atmosphere B due to pressure of the fluid as the seal object within the sealed space A. However, considering the vibration of the rotary shaft
102
in the diameter direction and an assembling error such that the rotary shaft
102
is inserted in the housing
100
in eccentric state, the rear surface support plate
203
is formed in such a manner as the inner diameter is larger than the outer diameter of the rotary shaft
102
to some extent. Therefore if the significantly high pressure is produced within the sealed space A, the rear surface of an inner circumference bent part
202
b
of the seal main body
202
enters a gap G between the inner diameter of the rear surface support plate
203
and the rotary shaft
102
. In some case, breakage is produced from the entering portion and the sealing performance may be deteriorated. Particularly, in such a case that the housing
100
and the rotary shaft
102
are eccentric to each other, the gap G becomes large in part in the circumferential direction. Therefore, in this part, the above-mentioned entering of the seal main body
202
is liable to occur.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a lip type seal which is excellent in pressure durability, where entering of a seal main body between a rear surface support plate and a rotary shaft due to pressure of a sealed space is prevented.
A lip type seal according to an embodiment of the present invention is provided with an outer ring part which is tightly fitted to a seal installation part of an inner circumference of a housing of an equipment, a seal main body which is fixed to the outer ring part and whose inner circumferential part extending in a bent state to the side of a sealed space is sealably brought into slidable contact with an outer circumferential surface of a rotary shaft inserted in the housing, a rear surface support plate which is arranged on the rear side of the seal main body and whose outer circumferential part together with the seal main body is fixed to the outer ring part, and a movable support plate which is engaged movably in a radial direction between the seal main body and the rear surface support plate and whose inner diameter is clearance fitted to the outer circumferential surface of the rotary shaft. The seal main body is supported through the movable support plate by the rear surface support plate.
In addition, “front surface” in the present specification means a surface facing the sealed space side, “rear surface” means a surface facing the opposite side of the sealed space, “front surface side” means the sealed space side, and “rear surface side” means the opposite side of the sealed space.


REFERENCES:
patent: 2405120 (1946-08-01), Evans
patent: 4583749 (1986-04-01), Hatch
patent: 5921555 (1999-07-01), Johnston
patent: 6279914 (2001-08-01), Yamanaka et al.
patent: 6290470 (2001-09-01), Okuno et al.

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